diff --git a/boehm-gc/configure.ac b/boehm-gc/configure.ac
--- a/boehm-gc/configure.ac
+++ b/boehm-gc/configure.ac
@@ -400,7 +400,7 @@ case "$host" in
  alpha*-*-linux*)
     machdep="alpha_mach_dep.lo"
     ;;
- i?86-*-solaris2.[[89]] | i?86-*-solaris2.1?)
+ i?86-*-solaris2.[[89]] | i?86-*-solaris2.1? | x86_64-*-solaris2.1?)
     AC_DEFINE(SOLARIS25_PROC_VDB_BUG_FIXED,1,[PROC_VDB in Solaris 2.5 gives wrong values for dirty bits])
     ;;
  mipstx39-*-elf*)
diff --git a/configure.ac b/configure.ac
--- a/configure.ac
+++ b/configure.ac
@@ -923,7 +923,7 @@ case "${target}" in
   i[[3456789]]86-*-sco*)
     noconfigdirs="$noconfigdirs gprof target-libgloss"
     ;;
-  i[[3456789]]86-*-solaris2*)
+  i[[3456789]]86-*-solaris2* | x86_64-*-solaris2.1[[0-9]]*)
     noconfigdirs="$noconfigdirs target-libgloss"
     ;;
   i[[3456789]]86-*-sysv4*)
diff --git a/gcc/ada/gcc-interface/Makefile.in b/gcc/ada/gcc-interface/Makefile.in
--- a/gcc/ada/gcc-interface/Makefile.in
+++ b/gcc/ada/gcc-interface/Makefile.in
@@ -1011,8 +1011,8 @@ ifeq ($(strip $(filter-out sparc% sun so
   endif
 endif
 
-ifeq ($(strip $(filter-out %86 solaris2%,$(arch) $(osys))),)
-  LIBGNAT_TARGET_PAIRS = \
+ifeq ($(strip $(filter-out %86 %x86_64 solaris2%,$(arch) $(osys))),)
+  LIBGNAT_TARGET_PAIRS_COMMON = \
   a-numaux.adb<a-numaux-x86.adb \
   a-numaux.ads<a-numaux-x86.ads \
   a-intnam.ads<a-intnam-solaris.ads \
@@ -1028,13 +1028,29 @@ ifeq ($(strip $(filter-out %86 solaris2%
   s-tpopsp.adb<s-tpopsp-solaris.adb \
   g-soliop.ads<g-soliop-solaris.ads
 
-  ifeq ($(strip $(MULTISUBDIR)),/amd64)
-    LIBGNAT_TARGET_PAIRS += \
-    system.ads<system-solaris-x86_64.ads
+  LIBGNAT_TARGET_PAIRS_32 = \
+  g-bytswa.adb<g-bytswa-x86.adb \
+  system.ads<system-solaris-x86.ads
+
+  LIBGNAT_TARGET_PAIRS_64 = \
+  system.ads<system-solaris-x86_64.ads
+
+  ifeq ($(strip $(filter-out %86 solaris2%,$(arch) $(osys))),)
+    ifeq ($(strip $(MULTISUBDIR)),/amd64)
+      LIBGNAT_TARGET_PAIRS = \
+      $(LIBGNAT_TARGET_PAIRS_COMMON) $(LIBGNAT_TARGET_PAIRS_64)
+    else
+      LIBGNAT_TARGET_PAIRS = \
+      $(LIBGNAT_TARGET_PAIRS_COMMON) $(LIBGNAT_TARGET_PAIRS_32)
+    endif
   else
-    LIBGNAT_TARGET_PAIRS += \
-    g-bytswa.adb<g-bytswa-x86.adb \
-    system.ads<system-solaris-x86.ads
+    ifeq ($(strip $(MULTISUBDIR)),/32)
+      LIBGNAT_TARGET_PAIRS = \
+      $(LIBGNAT_TARGET_PAIRS_COMMON) $(LIBGNAT_TARGET_PAIRS_32)
+    else
+      LIBGNAT_TARGET_PAIRS = \
+      $(LIBGNAT_TARGET_PAIRS_COMMON) $(LIBGNAT_TARGET_PAIRS_64)
+    endif
   endif
 
   TOOLS_TARGET_PAIRS=mlib-tgt-specific.adb<mlib-tgt-specific-solaris.adb
diff --git a/gcc/config.gcc b/gcc/config.gcc
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -1369,7 +1369,7 @@ i[34567]86-*-rtems*)
 	tm_file="${tm_file} i386/unix.h i386/att.h dbxelf.h elfos.h i386/i386elf.h i386/rtemself.h rtems.h newlib-stdint.h"
 	tmake_file="${tmake_file} i386/t-rtems t-rtems"
 	;;
-i[34567]86-*-solaris2*)
+i[34567]86-*-solaris2* | x86_64-*-solaris2.1[0-9]*)
 	tm_file="${tm_file} i386/unix.h i386/att.h ${sol2_tm_file}"
 	# Set default arch_32 to pentium4, tune_32 to generic like the other
 	# i386 targets, although config.guess defaults to i386-pc-solaris2*.
@@ -3529,7 +3529,7 @@ case ${target} in
 	  i[34567]86-*-gnu*)
 		tmake_file="${tmake_file} i386/t-fprules-softfp soft-fp/t-softfp i386/t-linux"
 		;;
-	i[34567]86-*-solaris2*)
+	i[34567]86-*-solaris2* | x86_64-*-solaris2.1[0-9]*)
 		tmake_file="${tmake_file} i386/t-fprules-softfp soft-fp/t-softfp"
 		;;
 	i[34567]86-*-cygwin* | i[34567]86-*-mingw* | x86_64-*-mingw*)
diff --git a/gcc/config.host b/gcc/config.host
--- a/gcc/config.host
+++ b/gcc/config.host
@@ -197,7 +197,7 @@ case ${host} in
   i370-*-opened* | i370-*-mvs* ) # IBM 360/370/390 Architecture
     host_xm_defines='FATAL_EXIT_CODE=12'
     ;;
-  i[34567]86-*-solaris2*)
+  i[34567]86-*-solaris2* | x86_64-*-solaris2.1[0-9]*)
     out_host_hook_obj=host-solaris.o
     host_xmake_file="${host_xmake_file} x-solaris"
     ;;
diff --git a/gcc/config/host-solaris.c b/gcc/config/host-solaris.c
--- a/gcc/config/host-solaris.c
+++ b/gcc/config/host-solaris.c
@@ -73,7 +73,7 @@ mmap_fixed (void *addr, size_t len, int 
 #elif defined(__sparc__)
 # define TRY_EMPTY_VM_SPACE	0x80000000
 #elif defined(__x86_64__)
-# define TRY_EMPTY_VM_SPACE	0x8000000000000000
+# define TRY_EMPTY_VM_SPACE	0x80000000000
 #elif defined(__i386__)
 # define TRY_EMPTY_VM_SPACE	0xB0000000
 #else
diff --git a/gcc/config/i386/sol2-bi.h b/gcc/config/i386/sol2-bi.h
--- a/gcc/config/i386/sol2-bi.h
+++ b/gcc/config/i386/sol2-bi.h
@@ -31,12 +31,16 @@ along with GCC; see the file COPYING3.  
 
 /* GNU as understands --32 and --64, but the native Solaris
    assembler requires -xarch=generic or -xarch=generic64 instead.  */
+#ifdef USE_GAS
+#define ASM_CPU32_DEFAULT_SPEC "--32"
+#define ASM_CPU64_DEFAULT_SPEC "--64"
+#else
+#define ASM_CPU32_DEFAULT_SPEC "-xarch=generic"
+#define ASM_CPU64_DEFAULT_SPEC "-xarch=generic64"
+#endif
+
 #undef ASM_CPU_SPEC
-#ifdef USE_GAS
-#define ASM_CPU_SPEC "%{m32:--32} %{m64:--64}"
-#else
-#define ASM_CPU_SPEC "%{m32:-xarch=generic} %{m64:-xarch=generic64}"
-#endif
+#define ASM_CPU_SPEC "%(asm_cpu_default)"
 
 /* Don't let i386/x86-64.h override i386/sol2.h version.  Still cannot use
    -K PIC with the Solaris 10+ assembler, it gives many warnings:
@@ -47,8 +51,7 @@ along with GCC; see the file COPYING3.  
 /* We do not need to search a special directory for startup files.  */
 #undef MD_STARTFILE_PREFIX
 
-/* No 64-bit default configurations.  */
-#define DEFAULT_ARCH32_P 1
+#define DEFAULT_ARCH32_P !TARGET_64BIT_DEFAULT
 
 #define ARCH64_SUBDIR "amd64"
 
diff --git a/gcc/config/i386/sol2.h b/gcc/config/i386/sol2.h
--- a/gcc/config/i386/sol2.h
+++ b/gcc/config/i386/sol2.h
@@ -59,6 +59,8 @@ along with GCC; see the file COPYING3.  
 #undef CPP_SPEC
 #define CPP_SPEC "%{,assembler-with-cpp:-P} %(cpp_subtarget)"
 
+#define ASM_CPU_DEFAULT_SPEC ""
+
 #define ASM_CPU_SPEC ""
  
 /* Don't include ASM_PIC_SPEC.  While the Solaris 8 and 9 assembler accepts
@@ -70,7 +72,8 @@ along with GCC; see the file COPYING3.  
 
 #define SUBTARGET_CPU_EXTRA_SPECS \
   { "cpp_subtarget",	 CPP_SUBTARGET_SPEC },		\
-  { "asm_cpu",		 ASM_CPU_SPEC }
+  { "asm_cpu",		 ASM_CPU_SPEC },		\
+  { "asm_cpu_default",	 ASM_CPU_DEFAULT_SPEC },	\
 
 #undef SUBTARGET_EXTRA_SPECS
 #define SUBTARGET_EXTRA_SPECS \
diff --git a/gcc/config/sol2-bi.h b/gcc/config/sol2-bi.h
--- a/gcc/config/sol2-bi.h
+++ b/gcc/config/sol2-bi.h
@@ -56,6 +56,16 @@
 #define DEF_ARCH64_SPEC(__str) "%{!m32:" __str "}"
 #endif
 
+#undef ASM_CPU_DEFAULT_SPEC
+#define ASM_CPU_DEFAULT_SPEC \
+(DEFAULT_ARCH32_P ? "\
+%{m64:" ASM_CPU64_DEFAULT_SPEC "} \
+%{!m64:" ASM_CPU32_DEFAULT_SPEC "} \
+" : "\
+%{m32:" ASM_CPU32_DEFAULT_SPEC "} \
+%{!m32:" ASM_CPU64_DEFAULT_SPEC "} \
+")
+
 /* This should be the same as LINK_ARCH32_SPEC_BASE, except with
    ARCH64_SUBDIR appended to the paths and /usr/ccs/lib is no longer
    necessary.  */
@@ -78,8 +88,14 @@
 #endif
 
 #ifdef USE_GLD
+#if DEFAULT_ARCH32_P
+#define ARCH_DEFAULT_EMULATION ARCH32_EMULATION
+#else
+#define ARCH_DEFAULT_EMULATION ARCH64_EMULATION
+#endif
 #define TARGET_LD_EMULATION "%{m32:-m " ARCH32_EMULATION "}" \
-			    "%{m64:-m " ARCH64_EMULATION "} "
+			    "%{m64:-m " ARCH64_EMULATION "}" \
+			    "%{!m32:%{!m64:-m " ARCH_DEFAULT_EMULATION "}} "
 #else
 #define TARGET_LD_EMULATION ""
 #endif
diff --git a/gcc/config/sparc/sol2.h b/gcc/config/sparc/sol2.h
--- a/gcc/config/sparc/sol2.h
+++ b/gcc/config/sparc/sol2.h
@@ -205,16 +205,6 @@ along with GCC; see the file COPYING3.  
 %{!mcpu*:%(asm_cpu_default)} \
 "
 
-#undef ASM_CPU_DEFAULT_SPEC
-#define ASM_CPU_DEFAULT_SPEC \
-(DEFAULT_ARCH32_P ? "\
-%{m64:" ASM_CPU64_DEFAULT_SPEC "} \
-%{!m64:" ASM_CPU32_DEFAULT_SPEC "} \
-" : "\
-%{m32:" ASM_CPU32_DEFAULT_SPEC "} \
-%{!m32:" ASM_CPU64_DEFAULT_SPEC "} \
-")
-
 #undef ASM_ARCH32_SPEC
 #define ASM_ARCH32_SPEC ""
 
diff --git a/gcc/configure.ac b/gcc/configure.ac
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -2168,7 +2168,7 @@ foobar:],[
 # Solaris 9/x86 as incorrectly emits an alias for a hidden symbol with
 # STV_HIDDEN, so disable .hidden support if so.
 case "${target}" in
-  i?86-*-solaris2*)
+  i?86-*-solaris2* | x86_64-*-solaris2.1[[0-9]]*)
     if test x$gcc_cv_as != x && test x$gcc_cv_objdump != x; then
       cat > conftest.s <<EOF
 .globl hidden
@@ -2423,7 +2423,7 @@ gcc_GAS_CHECK_FEATURE([cfi directives], 
 	  gcc_cv_as_cfi_directive=no
 	else
 	  case "$target" in
-	    i?86-*-solaris2.1[[0-9]]*)
+	    i?86-*-solaris2.1[[0-9]]* | x86_64-*-solaris2.1[[0-9]]*)
 	      # On Solaris/x86, make sure that GCC and gas agree on using
 	      # read-only .eh_frame sections for 64-bit.
 	      if $gcc_cv_as --64 -o conftest.o conftest.s > /dev/null 2>&1 && \
@@ -2627,7 +2627,7 @@ else
              foo:
 	     '
            ;;
-         i?86-*-solaris2*)
+         i?86-*-solaris2* | x86_64-*-solaris2.1[[0-9]]*)
 	   conftest_s='
                .group foo,.text%foo,#comdat
                .section .text%foo, "ax", @progbits
@@ -2805,12 +2805,16 @@ foo:	.long	25
 	tls_first_major=2
 	tls_first_minor=17
 	;;
-  i[34567]86-*-*)
+  i[34567]86-*-* | x86_64-*-solaris2.1[0-9]*)
     case "$target" in
       i[34567]86-*-solaris2.*)
 	on_solaris=yes
 	tga_func=___tls_get_addr
 	;;
+      x86_64-*-solaris2.1[0-9]*)
+	on_solaris=yes
+	tga_func=__tls_get_addr
+        ;;
       *)
 	on_solaris=no
 	;;
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -2957,6 +2957,8 @@ information are.
 @item
 @uref{#alpha-dec-osf51,,alpha*-dec-osf5.1}
 @item
+@uref{#amd64-x-solaris210,,amd64-*-solaris2.10}
+@item
 @uref{#arm-x-elf,,arm-*-elf}
 @item
 @uref{#avr,,avr}
@@ -3057,6 +3059,8 @@ information are.
 @item
 @uref{#x86-64-x-x,,x86_64-*-*, amd64-*-*}
 @item
+@uref{#x86-64-x-solaris210,,x86_64-*-solaris2.1[0-9]*}
+@item
 @uref{#xtensa-x-elf,,xtensa*-*-elf}
 @item
 @uref{#xtensa-x-linux,,xtensa*-*-linux*}
@@ -3157,6 +3161,13 @@ provide a fix shortly.
 @html
 <hr />
 @end html
+@heading @anchor{amd64-x-solaris210}amd64-*-solaris2.1[0-9]*
+
+This is a synonym for @samp{x86_64-*-solaris2.1[0-9]*}.
+
+@html
+<hr />
+@end html
 @heading @anchor{arm-x-elf}arm-*-elf
 ARM-family processors.  Subtargets that use the ELF object format
 require GNU binutils 2.13 or newer.  Such subtargets include:
@@ -3537,10 +3548,10 @@ you have the patch installed, you can co
 @end html
 @heading @anchor{ix86-x-solaris210}i?86-*-solaris2.10
 Use this for Solaris 10 or later on x86 and x86-64 systems.  This
-configuration is supported by GCC 4.0 and later versions only.  Unlike
-@samp{sparcv9-sun-solaris2*}, there is no corresponding 64-bit
-configuration like @samp{amd64-*-solaris2*} or @samp{x86_64-*-solaris2*}.
-@c FIXME: will there ever be?
+configuration is supported by GCC 4.0 and later versions only.  Starting
+with GCC 4.7, there is also a 64-bit @samp{amd64-*-solaris2.1[0-9]*} or
+@samp{x86_64-*-solaris2.1[0-9]*} configuration that corresponds to
+@samp{sparcv9-sun-solaris2*}.
 
 It is recommended that you configure GCC to use the GNU assembler, in
 @file{/usr/sfw/bin/gas}.  The versions included in Solaris 10, from GNU
@@ -4400,6 +4411,22 @@ both 64-bit x86-64 and 32-bit x86 code (
 @html
 <hr />
 @end html
+@heading @anchor{x86-64-x-solaris2.10}x86_64-*-solaris2.1[0-9]*
+
+GCC also supports the x86-64 architecture implemented by the AMD64
+processor (@samp{amd64-*-*} is an alias for @samp{x86_64-*-*}) on
+Solaris 10 or later.  Unlike other systems, without special options a
+bi-arch compiler is built which generates 32-bit code by default, but
+can generate 64-bit x86-64 code with the @option{-m64} switch.  Since
+GCC 4.7, there is also configuration that defaults to 64-bit code, but
+can generate 32-bit code with @option{-m32}.  To configure and build
+this way, you have to provide all support libraries like @file{libgmp}
+as 64-bit code, configure with @option{--target=x86_64-pc-solaris2.1x}
+and @samp{CC=gcc -m64}.
+
+@html
+<hr />
+@end html
 @heading @anchor{xtensa-x-elf}xtensa*-*-elf
 
 This target is intended for embedded Xtensa systems using the
diff --git a/gcc/testsuite/gcc.misc-tests/linkage.exp b/gcc/testsuite/gcc.misc-tests/linkage.exp
--- a/gcc/testsuite/gcc.misc-tests/linkage.exp
+++ b/gcc/testsuite/gcc.misc-tests/linkage.exp
@@ -46,7 +46,8 @@ if { [isnative] && ![is_remote host] } t
 		set native_cflags "-xarch=v9"
 	    }
 	}
-	if  [istarget "i?86*-*-solaris2*"] {
+	if  {[istarget "i?86*-*-solaris2*"]
+	     || [istarget "x86_64-*-solaris2.1\[0-9\]*"]} {
 	    set file_string [exec file "linkage-x.o"]
 	    if [ string match "*64*" $file_string ] {
 		set native_cflags "-xarch=amd64"
diff --git a/gnattools/configure.ac b/gnattools/configure.ac
--- a/gnattools/configure.ac
+++ b/gnattools/configure.ac
@@ -81,7 +81,7 @@ case "${target}" in
   sparc-sun-solaris*)
     TOOLS_TARGET_PAIRS="mlib-tgt-specific.adb<mlib-tgt-specific-solaris.adb"
     ;;
-  *86-*-solaris2*)
+  *86-*-solaris2* | x86_64-*-solaris2.1[[0-9]]*)
     TOOLS_TARGET_PAIRS="mlib-tgt-specific.adb<mlib-tgt-specific-solaris.adb"
     ;;
   *86-*-linux* \
diff --git a/libcpp/configure.ac b/libcpp/configure.ac
--- a/libcpp/configure.ac
+++ b/libcpp/configure.ac
@@ -145,7 +145,7 @@ case $target in
 	ia64-*-* | \
 	hppa*64*-*-* | \
 	i[34567]86-*-darwin* | \
-	i[34567]86-*-solaris2.1[0-9]* | \
+	i[34567]86-*-solaris2.1[0-9]* | x86_64-*-solaris2.1[0-9]* | \
 	i[34567]86-w64-mingw* | \
 	mips*-*-* | \
 	mmix-*-* | \
diff --git a/libgcc/config.host b/libgcc/config.host
--- a/libgcc/config.host
+++ b/libgcc/config.host
@@ -188,7 +188,7 @@ case ${host} in
   tmake_file="$tmake_file $cpu_type/t-sol2"
   extra_parts="gmon.o crtbegin.o crtend.o"
   case ${host} in
-    i?86-*-solaris2.1[0-9]*)
+    i?86-*-solaris2.1[0-9]* | x86_64-*-solaris2.1[0-9]*)
       # Solaris 10+/x86 provides crt1.o, crti.o, crtn.o, and gcrt1.o as
       # part of the base system.
       ;;
@@ -378,7 +378,7 @@ i[34567]86-*-rtems*)
 	extra_parts="crtbegin.o crtend.o crti.o crtn.o"
 	tmake_file="${tmake_file} t-crtin i386/t-softfp i386/t-crtstuff t-rtems"
 	;;
-i[34567]86-*-solaris2*)
+i[34567]86-*-solaris2* | x86_64-*-solaris2.1[0-9]*)
 	tmake_file="$tmake_file i386/t-crtfm"
 	extra_parts="$extra_parts crtfastmath.o"
 	md_unwind_header=i386/sol2-unwind.h
@@ -692,7 +692,7 @@ i[34567]86-*-darwin* | x86_64-*-darwin* 
   i[34567]86-*-kfreebsd*-gnu | x86_64-*-kfreebsd*-gnu | \
   i[34567]86-*-linux* | x86_64-*-linux* | \
   i[34567]86-*-gnu* | \
-  i[34567]86-*-solaris2* | \
+  i[34567]86-*-solaris2* | x86_64-*-solaris2.1[0-9]* | \
   i[34567]86-*-cygwin* | i[34567]86-*-mingw* | x86_64-*-mingw* | \
   i[34567]86-*-freebsd* | x86_64-*-freebsd*)
 	if test "${host_address}" = 32; then
diff --git a/libgcc/configure.ac b/libgcc/configure.ac
--- a/libgcc/configure.ac
+++ b/libgcc/configure.ac
@@ -207,7 +207,7 @@ esac
 # Link with -nostartfiles -nodefaultlibs since neither are present while
 # building libgcc.
 case ${host} in
-i?86-*-solaris2*)
+i?86-*-solaris2* | x86_64-*-solaris2.1[[0-9]]*)
   cat > conftest.s <<EOF
 	.section	.eh_frame,"a",@unwind
 	.zero	4
diff --git a/libgo/config/libtool.m4 b/libgo/config/libtool.m4
--- a/libgo/config/libtool.m4
+++ b/libgo/config/libtool.m4
@@ -1296,7 +1296,7 @@ s390*-*linux*|s390*-*tpf*|sparc*-*linux*
       case $lt_cv_prog_gnu_ld in
       yes*)
         case $host in
-        i?86-*-solaris*)
+        i?86-*-solaris* | x86_64-*-solaris2.1[[0-9]]*)
           LD="${LD-ld} -m elf_x86_64"
           ;;
         sparc*-*-solaris*)
diff --git a/libjava/configure.host b/libjava/configure.host
--- a/libjava/configure.host
+++ b/libjava/configure.host
@@ -141,6 +141,9 @@ case "${host}" in
 		libgcj_flags="${libgcj_flags} -ffloat-store" ;;
 	esac
 	libgcj_flags="${libgcj_flags} -fomit-frame-pointer"
+	# On Solaris we have defined 'sun' which later conflicts with 
+	# namespace usage. So to work this away we use the below undefine.
+	libgcj_flags="${libgcj_flags} -Usun"
 	libgcj_cxxflags=
 	libgcj_cflags=
 	DIVIDESPEC=-fno-use-divide-subroutine
@@ -285,6 +288,10 @@ EOF
 	sysdeps_dir=i386
 	DIVIDESPEC=-f%{m32:no-}%{!m32:%{!m64:no-}}%{m64:}use-divide-subroutine
 	;;
+  x86_64-*-solaris2.1[0-9]* )
+	sysdeps_dir=i386
+	DIVIDESPEC=-f%{m32:no-}use-divide-subroutine
+	;;
   mips-sgi-irix6* )
 	can_unwind_signal=yes
 	sysdeps_dir=mips
@@ -322,7 +329,7 @@ EOF
 	DIVIDESPEC=-fuse-divide-subroutine
 	CHECKREFSPEC=-fcheck-references
 	;;
-  i?86-*-solaris2*)
+  i?86-*-solaris2* | x86_64-*-solaris2.1[0-9]*)
 	can_unwind_signal=yes
 	;;
   *-*-freebsd*)
